Haskell Free Library and Opera House. Derby Line, Vermont/Stanstead, Quebec. The Haskell Free Library and Opera House is a neoclassical building that straddles the international border in Rock Island (now part of Stanstead, Quebec) and Derby Line, Vermont. The Opera House opened on June 7, 1904, and was built on the border between Canada and the United States. The library collection and the opera stage are located in Stanstead, but the door and most opera seats are located in Derby Line. Because of this, the Haskell is sometimes called "the only library in the U.S.A. with no books" and "the only opera house in the U.S.A. with no stage". Its two addresses are 93 Caswell Avenue, Derby Line, Vermont and 1 Church Street, Stanstead, Quebec. A thick black line runs beneath the seats of the opera house and diagonally across the center of the library's reading room to mark the international boundary. The stage and half of the seats are in Canada, the remainder of the opera hall is in the US. The library has a collection of more than 20,000 books in French and English, and is open to the public 38 hours a week. The building is recognized as a historic site in both countries. In the United States, it has been registered in the National Register of Historic Places since 1976. In Canada, it was designated a National Historic Site of Canada in 1985 and has been a provincial heritage site since 1977.